Solve for $x$ and $y$ using elimination. ${-3x+5y = 20}$ ${3x+3y = 36}$
Explanation: We can eliminate $x$ by adding the equations together when the $x$ coefficients have opposite signs. Add the equations together. Notice that the terms $-3x$ and $3x$ cancel out. $8y = 56$ $\dfrac{8y}{{8}} = \dfrac{56}{{8}}$ ${y = 7}$ Now that you know ${y = 7}$ , plug it back into $\thinspace {-3x+5y = 20}\thinspace$ to find $x$ ${-3x + 5}{(7)}{= 20}$ $-3x+35 = 20$ $-3x+35{-35} = 20{-35}$ $-3x = -15$ $\dfrac{-3x}{{-3}} = \dfrac{-15}{{-3}}$ ${x = 5}$ You can also plug ${y = 7}$ into $\thinspace {3x+3y = 36}\thinspace$ and get the same answer for $x$ : ${3x + 3}{(7)}{= 36}$ ${x = 5}$